Season 4. Promising start and was atmospheric but the reveal was totally lame and once again gives the message that its OK to kill if you have a reason, apparently. Huge holes in the plot. Unbelievable science that was the whole motivation for the scientists was brushed over in literally 5 seconds. I have no issues with strong female leads, but do they have to be sweary, shouty and moody all the time? Roles like these have been overdone and are tiresome.